US3524146A - Semiconductor laser having a brewster angle face and a remote reflector - Google Patents

Semiconductor laser having a brewster angle face and a remote reflector Download PDF

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Publication number
US3524146A
US3524146A US715687A US3524146DA US3524146A US 3524146 A US3524146 A US 3524146A US 715687 A US715687 A US 715687A US 3524146D A US3524146D A US 3524146DA US 3524146 A US3524146 A US 3524146A
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United States
Prior art keywords
brewster angle
reflector
laser
zone
semiconductor laser
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Expired - Lifetime
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US715687A
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English (en)
Inventor
Eugen Mohn
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Universitaet Bern
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Universitaet Bern
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures

Definitions

  • a laser oscillator provided with a laser diode wherein light rays are reflected back and forth and amplified in a pn-transition zone and at least one of the oscillator reflectors is at a distance from the laser diode. Reflection losses at the lateral surface of the diode facing the distant reflector are averted by inclining that surface at the Brewster angle relative to the direction of the light rays passing through the pn-transition zone.
  • two opposite, parallel lateral surfaces of a small crystal block constituting the diode generally are used as reflectors to reflect the light rays back and forth which are generated by the action of an electric potential in the pn-transition zone of the diode.
  • the rays undergo amplification at each pass through that zone.
  • a laser oscillator has been devised which has a laser diode provided with a pn-transition layer which is disposed between two reflectors between which the light rays, passing through the pn-transition layer, are reflected back and forth and amplified. At least one of these reflectors is at a distance from the laser diode and reflection losses on the lateral surface of the diode facing the reflector are averted.
  • the lateral surface of the laser diode facing the reflector at a distance is inclined at the Brewster angle relative to the direction of the rays passing through the pn-transition layer.
  • the sole figure in the drawing is a schematic of a laser oscillator with laser diode.
  • the laser oscillator has as amplifying element a laser diode 1 which, by way of example, may be a gallium arsenide crystal doped with zinc in the p-zone and with tellurium in the n-zone.
  • Crystal 1 has two parallel rectangular principal surfaces 2 and 2', respectively.
  • Surface 2 is fastened to an electroconductive support 3, and surface 2' is provided with an electrode 4.
  • Lateral surface is in vertical position relative to surfaces 2 and 2', while the opposite lateral surface 6 is inclined at an angle a which equals the Brewster angle for the boundary layer crystal-air.
  • the pn-transition zone (or layer) 7 is in parallel to the principal surfaces 2 and 2', and its edges 8 and 9, disposed in lateral surfaces 5 and 6, respectively, are parallel to each other.
  • the two other lateral surfaces 10 and 11 if crystal 1 are parallel to the drawing plane; however, their exact position is immaterial.
  • One of the two reflectors between which the amplifier element 1 of the laser oscillator must be positioned is formed by the lateral surface 5 of element 1 itself.
  • Surface 5 is reflective in such a manner that a light my passing through transition zone 7 falling on this surface 5 vertically, is reflected to a great extent. Reflector 5 also permits the emergence of a usable ray 12 from the oscillator.
  • the other reflector of the laser oscillator is a concave mirror 13, disposed at distance of e.g., 17 mm. from amplifier element 1.
  • Mirror or reflector 13 is struck at its center by light ray 14 emerging from edge 9 of transition zone 7.
  • Mirror 13 may be produced, for instance, by vaporizing a gold layer on the convex s de of a planoconvex, cylindrical, spherical or ellipsoidal lens 15.
  • a light ray is generated and amplified in transition zone 7.
  • the electric field intensity E of the light ray is linearly polarized vertically to pntransition layer 7, as shown by an arrow in the drawing.
  • the thus polarized light ray passes, without any reflection losses, through lateral surface 6 which is inclined at the Brewster angle a and hence is refracted from the normal 17 toward surface 6.
  • a Brewster angle of substantially corresponds to the index of refraction of gallium arsenide. It should be pointed out that any suitable semiconductor elements containing any suiable impurities may be employed in lieu of gallium arsenide.
  • the ray is reflected practically at mirror 13 and returns into pn-transition layer 7 through lateral surface 6 without reflection loss. It then again is reflected at reflector 5, and the passing repeated. At each passage through transition zone 7, an amplification of the light occurs.
  • the light exit edges 8 and 9 emit the light the more uniformly, the better the quality of crystal 1. This quality depends on uniform structure and uniform doping. Irregularities in the crystal cause a concentration of the light exit on light spots, whereby a linear polarization, vertical to polarization direction 16, can occur, which, however, is undesirable.
  • the optical path of the light rays in the pn-transition zone is equally long at all points.
  • lateral surface 6 is inclined at the Brewster angle relative to the direction of the light rays passing through the transition zone 7, but is so disposed that its edges 8 and 9 are not in parallel, the optical path of the rays is not the same at all points. Therefore, the resonance frequency conditions of the laser oscillator along the cross section of the flat, ribbon-shaped bundle of rays reflected back and forth in the oscillator are not alike at all points of the cross section.
  • Lateral surface 5 can be a cleavage face of crystal 1 or a ground surface.
  • Lateral surface 6 is ground. Because of the small size of the laser diode whose principal surfaces are on the order of approximately 1 mm. it is optance, both lateral surfaces of the laser diode facing the reflectors are inclined at the Brewster angle relative to the direction of the rays passing through the pn-transition zone, preferably in parallel. The latter has the advantage that cleavage faces of the crystal can be used as lateral surfaces and the pn-transition layer is produced at the Brewster angle relative to these surfaces upon doping.
  • a laser oscillator comprising a laser diode as an amplifying element and a reflector at each side of said element; said diode having an n-zone, a p-zone and a pntransition zone; applied current-means generating light rays which pass through said pn-transition zone and are reflected back and forth through said zone and are amplified at each passage; at least one of said reflectors being at a predetermined distance from said diode; the lateral surface of said diode facing said distant reflector being inclined at the Brewster angle relative to the direction of the rays passing through said pn-transition zone; thereby averting reflection losses.
  • the laser diode as defined in claim 1, wherein the laser diode is a gallium arsenide crystal having as impurities zinc in the p-zone and tellurium in the n-zone; the Brewster angle for said crystal being substantially 75.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)
  • Treatment Of Fiber Materials (AREA)
US715687A 1967-05-11 1968-03-25 Semiconductor laser having a brewster angle face and a remote reflector Expired - Lifetime US3524146A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH666767A CH455078A (de) 1967-05-11 1967-05-11 Laseroszillator mit einer Laserdiode

Publications (1)

Publication Number Publication Date
US3524146A true US3524146A (en) 1970-08-11

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ID=4313128

Family Applications (1)

Application Number Title Priority Date Filing Date
US715687A Expired - Lifetime US3524146A (en) 1967-05-11 1968-03-25 Semiconductor laser having a brewster angle face and a remote reflector

Country Status (5)

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US (1) US3524146A (de)
CH (1) CH455078A (de)
DE (2) DE1589971A1 (de)
GB (1) GB1210331A (de)
NL (1) NL6716265A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688218A (en) * 1971-01-29 1972-08-29 Us Army Stimulated radiation cavity reflector
US4573158A (en) * 1981-08-27 1986-02-25 Kokusai Denshin Denwa Kabushiki Kaisha Distributed feedback semiconductor laser

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3728568A1 (de) * 1987-08-27 1989-03-16 Telefunken Electronic Gmbh Halbleiterlaseranordnung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3295911A (en) * 1963-03-15 1967-01-03 Bell Telephone Labor Inc Semiconductor light modulators
US3462711A (en) * 1967-08-28 1969-08-19 Bell Telephone Labor Inc Electro-optic diode modulators

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3295911A (en) * 1963-03-15 1967-01-03 Bell Telephone Labor Inc Semiconductor light modulators
US3462711A (en) * 1967-08-28 1969-08-19 Bell Telephone Labor Inc Electro-optic diode modulators

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688218A (en) * 1971-01-29 1972-08-29 Us Army Stimulated radiation cavity reflector
US4573158A (en) * 1981-08-27 1986-02-25 Kokusai Denshin Denwa Kabushiki Kaisha Distributed feedback semiconductor laser

Also Published As

Publication number Publication date
DE1763329A1 (de) 1972-01-13
DE1589971A1 (de) 1972-03-16
GB1210331A (en) 1970-10-28
CH455078A (de) 1968-04-30
NL6716265A (de) 1968-11-12

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